That's a good question. Veterinarians need sound withdrawal interval information to use drugs in food animals in a safe manner, and in compliance with federal extralabel drug use regulations. A great source of withdrawal interval information is the Food Animal Residue Avoidance Databank. FARAD is a National Food Safety Project of the Department of Agriculture, Cooperative State Research, Education, and Extension Service.
FARAD personnel use residue and pharmacokinetic information to help develop withdrawal recommendations for veterinarians anticipating the extralabel use of approved drugs in food animals. Their expert assistance is available from Eastern and Western Regional Access Centers, which are accessible by calling 888-USFARAD (888-873-2723). The centers operate during normal business hours. Most questions can be answered immediately; however, complex responses may require a couple of days.
FARAD is also accessible on the Internet at www.farad.org. Withdrawal interval questions can be submitted as e-mails through the site.
I also like to remind veterinarians that FARAD prepared a series of feature articles titled "FARAD Digest" that were published in the JAVMA between 1997 and 2000. The articles addressed the extralabel use of oxytetracycline, tranquilizers and general anesthetics, nonsteroidal anti-inflammatory drugs, ivermectin, and moxidectin, as well as the prevention of antimicrobial residues in veal calves fed colostrum.
FARAD also works collaboratively with the United States Pharmacopeia Veterinary Medicine Advisory Panel. This panel creates veterinary drug information monographs, and FARAD develops the extralabel withdrawal intervals for specific extralabel indications. Currently, the USP Veterinary Drug Information monographs on antimicrobial use in animals are available online at www.usp.org/veterinary/index.htm.